This may not be relevant for developer, is oriented more to user testing.
Checklist for testing ROME and Rock ISOs
I use the checklists as a guide for what to test, I do not send them anywhere because I doubt we have anyone with time to read them and follow through.
Then I report issues in IRC (OM-Chat), or file a bug report. Sometimes when devs are working on something we also need to tell them it works. For example I know that right now a couple of them are working on things with Wayland and our Spins.
For users this keeps things simple but the more different users and hardware tested on the better (betterer) we can make things,